On Fri, Sep 29, 2023 at 5:08 PM Maxime Coquelin
[off-list ref] wrote:

On 9/25/23 04:57, Jason Wang wrote:

quoted

On Thu, Sep 21, 2023 at 10:07 PM Cindy Lu [off-list ref] wrote:

quoted

On Mon, Sep 18, 2023 at 4:49 PM Jason Wang [off-list ref] wrote:

quoted

On Tue, Sep 12, 2023 at 11:01 AM Cindy Lu [off-list ref] wrote:

quoted

In VDUSE_GET_RECONNECT_INFO, the Userspace App can get the map size
and The number of mapping memory pages from the kernel. The userspace
App can use this information to map the pages.

Signed-off-by: Cindy Lu <redacted>
---
  drivers/vdpa/vdpa_user/vduse_dev.c | 15 +++++++++++++++
  include/uapi/linux/vduse.h         | 15 +++++++++++++++
  2 files changed, 30 insertions(+)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 680b23dbdde2..c99f99892b5c 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c

@@ -1368,6 +1368,21 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                 ret = 0;
                 break;
         }
+       case VDUSE_GET_RECONNECT_INFO: {
+               struct vduse_reconnect_mmap_info info;
+
+               ret = -EFAULT;
+               if (copy_from_user(&info, argp, sizeof(info)))
+                       break;
+
+               info.size = PAGE_SIZE;
+               info.max_index = dev->vq_num + 1;
+
+               if (copy_to_user(argp, &info, sizeof(info)))
+                       break;
+               ret = 0;
+               break;
+       }
         default:
                 ret = -ENOIOCTLCMD;
                 break;

diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
index d585425803fd..ce55e34f63d7 100644
--- a/include/uapi/linux/vduse.h
+++ b/include/uapi/linux/vduse.h

@@ -356,4 +356,19 @@ struct vhost_reconnect_vring {
         _Bool avail_wrap_counter;
  };

+/**
+ * struct vduse_reconnect_mmap_info
+ * @size: mapping memory size, always page_size here
+ * @max_index: the number of pages allocated in kernel,just
+ * use for check
+ */
+
+struct vduse_reconnect_mmap_info {
+       __u32 size;
+       __u32 max_index;
+};

One thing I didn't understand is that, aren't the things we used to
store connection info belong to uAPI? If not, how can we make sure the
connections work across different vendors/implementations. If yes,
where?

Thanks

The process for this reconnecttion  is
A.The first-time connection
1> The userland app checks if the device exists
2>  use the ioctl to create the vduse device
3> Mapping the kernel page to userland and save the
App-version/features/other information to this page
4>  if the Userland app needs to exit, then the Userland app will only
unmap the page and then exit

B, the re-connection
1> the userland app finds the device is existing
2> Mapping the kernel page to userland
3> check if the information in shared memory is satisfied to
reconnect,if ok then continue to reconnect
4> continue working

  For now these information are all from userland,So here the page will
be maintained by the userland App
in the previous code we only saved the api-version by uAPI .  if  we
need to support reconnection maybe we need to add 2 new uAPI for this,
one of the uAPI is to save the reconnect  information and another is
to get the information

maybe something like

struct vhost_reconnect_data {
uint32_t version;
uint64_t features;
uint8_t status;
struct virtio_net_config config;
uint32_t nr_vrings;
};

Probably, then we can make sure the re-connection works across
different vduse-daemon implementations.

+1, we need to have this defined in the uAPI to support interoperability
across different VDUSE userspace implementations.

quoted

quoted

#define VDUSE_GET_RECONNECT_INFO _IOR (VDUSE_BASE, 0x1c, struct
vhost_reconnect_data)

#define VDUSE_SET_RECONNECT_INFO  _IOWR(VDUSE_BASE, 0x1d, struct
vhost_reconnect_data)

Not sure I get this, but the idea is to map those pages to user space,
any reason we need this uAPI?

It should not be necessary if the mmapped layout is properly defined.

Thanks,
Maxime

Sure , I will use mmap to sync the reconnect status
Thanks
cindy

quoted

Thanks

quoted

Thanks
Cindy

quoted

quoted

+
+#define VDUSE_GET_RECONNECT_INFO \
+       _IOWR(VDUSE_BASE, 0x1b, struct vduse_reconnect_mmap_info)
+
  #endif /* _UAPI_VDUSE_H_ */
--
2.34.3